In recently years, an SSD (Solid State Drive) that uses a nonvolatile memory unit such as a flash memory in place of an HDD (Hard Disk Drive) as a storage device of information equipment such as a personal computer attracts notice. Utilization of the SSD as a file system of a personal computer (PC) is now being increased.
Much personal information and user data of a user of a PC is recorded in a file system of the type as mentioned above and seriousness of leakage of information recorded in the file system has been increased to such an extent that it causes social problems. Accordingly, in the case that a nonvolatile memory unit is to be discarded, it may be unavoidable to erase data in a nonvolatile memory which is mounted on the nonvolatile memory unit.
Therefore, an erase command is input into an interface from the outside in order to erase data in the nonvolatile memory concerned and a nonvolatile memory controller controls the nonvolatile memory to erase the data in it on the basis of the erase command. Thus, it may be unavoidable to use data erasing equipment that includes an interface which is allowed to issue the erase command when the data in the nonvolatile memory is to be erased.
However, in the case that the nonvolatile memory controller is failed, it may be difficult to erase the data in the nonvolatile memory regardless of use of the data erasing equipment. Therefore, secret data such as personal information and the like may be left in the nonvolatile memory unit.
In a failed nonvolatile memory unit, it may be possible to read out data in the nonvolatile memory by replacing a failed nonvolatile memory controller included in the memory unit with a new one. In addition, it may be also possible to read out the data by detaching the nonvolatile memory mounted on the memory unit from the unit and gaining access to the detached nonvolatile memory.
Thus, discarding the failed nonvolatile memory unit as it is may lead to information leakage. Therefore, in general, the failed nonvolatile memory unit is physically destroyed by punching it or by taking other measures. However, any sufficient result may not be obtained unless all nonvolatile memories mounted on the failed nonvolatile memory unit are physically destroyed. Therefore, it is expected to favorably destroy the memories.
However, the number of nonvolatile memories mounted on the nonvolatile memory unit is increased with an increase in storage capacity of late years. As a result, much time is taken to destroy all the nonvolatile memories included in the memory unit and the processing man-hour is increased accordingly.